Making chunk_size=None behavior for n_jobs=1 explicit

src/spikeinterface/core/job_tools.py

@@ -131,6 +131,8 @@ def split_job_kwargs(mixed_kwargs):
 def divide_segment_into_chunks(num_frames, chunk_size):
     if chunk_size is None:
         chunks = [(0, num_frames)]
+    elif chunk_size > num_frames:
+        chunks = [(0, num_frames)]
     else:
         n = num_frames // chunk_size
 
@@ -245,12 +247,12 @@ def ensure_chunk_size(
         else:
             raise ValueError("chunk_duration must be str or float")
     else:
+        # Edge case to define single chunk per segment for n_jobs=1.
+        # All chunking parameters equal None mean single chunk per segment
         if n_jobs == 1:
-            # not chunk computing
-            # TODO Discuss, Sam, is this something that we want to do?
-            # Even in single process mode, we should chunk the data to avoid loading the whole thing into memory I feel
-            # Am I wrong?
-            chunk_size = None
+            num_segments = recording.get_num_segments()
+            samples_in_larger_segment = max([recording.get_num_samples(segment) for segment in range(num_segments)])
+            chunk_size = samples_in_larger_segment
         else:
             raise ValueError("For n_jobs >1 you must specify total_memory or chunk_size or chunk_memory")
 

src/spikeinterface/core/tests/test_job_tools.py

@@ -42,11 +42,9 @@ def test_ensure_n_jobs():
 
 
 def test_ensure_chunk_size():
-    recording = generate_recording(num_channels=2)
+    recording = generate_recording(num_channels=2, durations=[5.0, 2.5])  # This is the default value for two semgents
     dtype = recording.get_dtype()
     assert dtype == "float32"
-    # make serializable
-    recording = recording.save()
 
     chunk_size = ensure_chunk_size(recording, total_memory="512M", chunk_size=None, chunk_memory=None, n_jobs=2)
     assert chunk_size == 32000000
@@ -69,6 +67,15 @@ def test_ensure_chunk_size():
     chunk_size = ensure_chunk_size(recording, chunk_duration="500ms")
     assert chunk_size == 15000
 
+    # Test edge case to define single chunk for n_jobs=1
+    chunk_size = ensure_chunk_size(recording, n_jobs=1, chunk_size=None)
+    chunks = divide_recording_into_chunks(recording, chunk_size)
+    assert len(chunks) == recording.get_num_segments()
+    for chunk in chunks:
+        segment_index, start_frame, end_frame = chunk
+        assert start_frame == 0
+        assert end_frame == recording.get_num_frames(segment_index=segment_index)
+
 
 def func(segment_index, start_frame, end_frame, worker_ctx):
     import os